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Sphingolipid metabolism correlates with cerebrospinal fluid Beta amyloid levels in Alzheimer's disease.

ABSTRACT: Sphingolipids are important in many brain functions but their role in Alzheimer's disease (AD) is not completely defined. A major limit is availability of fresh brain tissue with defined AD pathology. The discovery that cerebrospinal fluid (CSF) contains abundant nanoparticles that include synaptic vesicles and large dense core vesicles offer an accessible sample to study these organelles, while the supernatant fluid allows study of brain interstitial metabolism. Our objective was to characterize sphingolipids in nanoparticles representative of membrane vesicle metabolism, and in supernatant fluid representative of interstitial metabolism from study participants with varying levels of cognitive dysfunction. We recently described the recruitment, diagnosis, and CSF collection from cognitively normal or impaired study participants. Using liquid chromatography tandem mass spectrometry, we report that cognitively normal participants had measureable levels of sphingomyelin, ceramide, and dihydroceramide species, but that their distribution differed between nanoparticles and supernatant fluid, and further differed in those with cognitive impairment. In CSF from AD compared with cognitively normal participants: a) total sphingomyelin levels were lower in nanoparticles and supernatant fluid; b) levels of ceramide species were lower in nanoparticles and higher in supernatant fluid; c) three sphingomyelin species were reduced in the nanoparticle fraction. Moreover, three sphingomyelin species in the nanoparticle fraction were lower in mild cognitive impairment compared with cognitively normal participants. The activity of acid, but not neutral sphingomyelinase was significantly reduced in the CSF from AD participants. The reduction in acid sphingomylinase in CSF from AD participants was independent of depression and psychotropic medications. Acid sphingomyelinase activity positively correlated with amyloid ?42 concentration in CSF from cognitively normal but not impaired participants. In dementia, altered sphingolipid metabolism, decreased acid sphingomyelinase activity and its lost association with CSF amyloid ?42 concentration, underscores the potential of sphingolipids as disease biomarkers, and acid sphingomyelinase as a target for AD diagnosis and/or treatment.

SUBMITTER: Fonteh AN

PROVIDER: S-EPMC4418746 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Sphingolipid metabolism correlates with cerebrospinal fluid Beta amyloid levels in Alzheimer's disease.

Fonteh Alfred N AN Ormseth Cora C Chiang Jiarong J Cipolla Matthew M Arakaki Xianghong X Harrington Michael G MG

PloS one 20150504 5

Sphingolipids are important in many brain functions but their role in Alzheimer's disease (AD) is not completely defined. A major limit is availability of fresh brain tissue with defined AD pathology. The discovery that cerebrospinal fluid (CSF) contains abundant nanoparticles that include synaptic vesicles and large dense core vesicles offer an accessible sample to study these organelles, while the supernatant fluid allows study of brain interstitial metabolism. Our objective was to characteriz ...[more]

PMID: 25938590

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Project description:Introduction: Amyloid beta 1-43 (A?43), with its additional C-terminal threonine residue, is hypothesized to play a role in early Alzheimer's disease pathology possibly different from that of amyloid beta 1-42 (A?42). Cerebrospinal fluid (CSF) A?43 has been suggested as a potential novel biomarker for predicting conversion from mild cognitive impairment (MCI) to dementia in Alzheimer's disease. However, the relationship between CSF A?43 and established imaging biomarkers of Alzheimer's disease has never been assessed. Materials and Methods: In this observational study, CSF A?43 was measured with ELISA in 89 subjects; 34 with subjective cognitive decline (SCD), 51 with MCI, and four with resolution of previous cognitive complaints. All subjects underwent structural MRI; 40 subjects on a 3T and 50 on a 1.5T scanner. Forty subjects, including 24 with SCD and 12 with MCI, underwent 18F-Flutemetamol PET. Seventy-eight subjects were assessed with 18F-fluorodeoxyglucose PET (21 SCD/7 MCI and 11 SCD/39 MCI on two different scanners). Ten subjects with SCD and 39 with MCI also underwent diffusion tensor imaging. Results: Cerebrospinal fluid A?43 was both alone and together with p-tau a significant predictor of the distinction between SCD and MCI. There was a marked difference in CSF A?43 between subjects with 18F-Flutemetamol PET scans visually interpreted as negative (37 pg/ml, n = 27) and positive (15 pg/ml, n = 9), p < 0.001. Both CSF A?43 and A?42 were negatively correlated with standardized uptake value ratios for all analyzed regions; CSF A?43 average rho -0.73, A?42 -0.74. Both CSF A? peptides correlated significantly with hippocampal volume, inferior parietal and frontal cortical thickness and axial diffusivity in the corticospinal tract. There was a trend toward CSF A?42 being better correlated with cortical glucose metabolism. None of the studied correlations between CSF A?43/42 and imaging biomarkers were significantly different for the two A? peptides when controlling for multiple testing. Conclusion: Cerebrospinal fluid A?43 appears to be strongly correlated with cerebral amyloid deposits in the same way as A?42, even in non-demented patients with only subjective cognitive complaints. Regarding imaging biomarkers, there is no evidence from the present study that CSF A?43 performs better than the classical CSF biomarker A?42 for distinguishing SCD and MCI.

Dataset Information

Sphingolipid metabolism correlates with cerebrospinal fluid Beta amyloid levels in Alzheimer's disease.

Publications

Sphingolipid metabolism correlates with cerebrospinal fluid Beta amyloid levels in Alzheimer's disease.

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